The 9,000 btu air conditioner unit has aged out. I'm studying replacing it, but also thinking of sailing next summer to the Mediterranean, where the plan would be to spend May-July of the next four years or so there and leave the boaton the hard the other months of the year.

Have read extensively on European AC conversions, and think these may be my options:

1) do not replace the 9,000 btu unit. Sail to Europe, buy a portable isolation transformer, and live without air conditioning over there for the next few years. Fix the U.S. air conditioning when we get back. (Cost= $400?)

2) Install an isolation transformer, do not replace the 9,000 btu unit, but use the existing 12,000 btu unit on 50 hertz in the Med (transformed to 115 volts) until we maybe burn up the motors. (cost $600 now?)

3) Replace the 9,000 btu unit with a new U.S. model. Add a Next Gen 115-volt generator, use generator for all AC needs while in Med. (cost= $7500?)

4) Replace both air conditioners with 230/240 volt, 50/60 hertz Webasto models, replace the waterheater element, replace the batterycharger, replace the AC panel and shore power inlet, and convert to a full AC system that would work both in the U.S. and Europe (cost= $5000?)

I'm there now and you may not need AC during those months but last summer was blistering and I would not want to repeat it without AC. I use two 16k btu Webasto units bought in US with a combination of continuous duty step down transformers and my inverter. The step downs, 3000 watts each, power the compressors. The inverter powers the blowers and raw water pumps. This was done because Webasto's blower motor supplier could not assure the blowers would work at 50hz.

I have no generator so this has to be run at dockside. High season in July and August and berths can be very expensive then especially in countries like Italy.

Why is everybody so fixed on AC I live in the tropics and shading if far easier. The AC on the boat has never been used it probably doesn't work anymore after 8 years ! Its also a lot healthier to acclimatise !

Years ago when I was stationed in Germany we took all our US 60 Uz appliances and used step down transformers and everything worked, everything. If you had a mechanical clock, it would run slow, the microwave sounded different but worked. I think maybe things aren't as sensitive as we believe or maybe just tougher.

Why is everybody so fixed on AC I live in the tropics and shading if far easier. The AC on the boat has never been used it probably doesn't work anymore after 8 years ! Its also a lot healthier to acclimatise !

One reason, I have a few times been anchored in the Bahamas or Caribbean when there was no breeze, temps in the mid 30s C and the mosquitoes or no-see-ums attacked. I saw four options for dealing with this: leave the hatches open and get eaten alive (also risking Zika, malaria or some other nasty disease), close the hatches and suffer the heat (I was never able to acclimatize to being locked up in a boat with no ventilation), hoist anchor in the middle of the night and head out to sea OR fire up the air conditioner if you have one.

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The water is always bluer on the other side of the ocean.

Sometimes it's necessary to state the obvious for the benefit of the oblivious.

One can make (or buy) screens for hatches that will block the bugs. But bugs in the Med aren't a huge problem.

If you choose to use a step down transformer you can extend the life of the motors by ensuring that the voltage to the motors stays at 120-130 instead of 100-110. Motors generate more heat at reduced voltage which is counter-intuitive to many people. Get a step down transformer that has taps so you can choose the optimal boat side voltage for your air conditioners.

We also are a US boat in the Med, albeit barely. Our AC system has three 120 Vac motors- the compressor, blower, and sea water recirc pump. All of mine were rated 120 Vac. 50/60 Hz. If your boat is the same then an isolation transformer that allows you to step down from 230 to 120 will solve that problem.

Don't forget to check the rest of your 120 V equipment- our inverter/charger is not rated for 50 Hz (although it seems to work okay).

To address your question as to if AC is needed, it depends on where you are. If you plan your trip to be north in July, you may be fine without it. It also depends on how attached you are to creature comforts!

I like my little Nexgen even though I have been having enough issues with it, my Daughter calls the thing my little buddy, 90% of them are no fault of the generator, it was fueldelivery issues. ( I hope)
It is nice to be able to completely charge batteries, make ice, run the toaster and a myriad of other things. I have given up on 12V appliances. At first I thought that was the way to go, but they are often much more expensive and don't work as well as 120 VAC ones. Yes I have a large inverter but once you start running all the electric luxuries a generator is nice to have, and maybe we will eventually acclimatize to the heat, but as we are now weekend warriors, living in an air conditioned house, if I can't cool the boat down, the wife had rather stay home and wait until cooler weather to go to the boat, so having AC means to me year round boat access as opposed to spring and fall.

This has nothing to do with the Med, we are in Fl, but installing a generator before you go to the Med will I think make you happier.

We have a 220V airco and cruise the med. We can only use the airco when plugged in shorepower. For the last 4 years this has not been a problem. In my experience the hottest places are in the harbours ( lack of wind and coastal pollution) and this is where I can use the airco. When moored we mostly get along without forced ventilation and only occasionally use our 12V fans. We cruise only in the summer. YMMV.

you may need an AC when it get to 99F/35C in some places , sometimes. In the harbors especially. The water also get warmer. So, water cooled AC will be sensetive. I have step down trafo. The AC compressor run on 125V/50Hz. But, the raw water pump runs 20% slower...And,if the water is 27C or so, compressor becomes overheated and the thermoswitch cut it off. The portable units is one economical solution. Also will work on the hard. I have 16000BTU marine Flagship aircon and 14000 BTU portable one. May run both in the dock with 32 Amp/220V. But, not with the genny. My 4,5kVa Panda have problems to deal wtih the one. Still working on it.